How Effective Were Pandemic Lockdowns ?

The Issue:

Lockdowns — mandatory orders to stay home and to close businesses and schools — were widely adopted worldwide during the global public health emergency caused by COVID 19 and have been hotly debated ever since. Governments believed that lockdowns were necessary to contain the spread of a dangerous and unpredictable pandemic, at a time when medical responses were very limited and the way COVID spread was unclear. However, there was pushback from those who worried that lockdowns were ineffective and economically and socially damaging. Over time, lockdowns were pulled back, particularly after new forms of medical intervention became available. But, the question of how effective the lockdowns were in containing COVID remains and has prompted extensive research aimed at drawing relevant lessons for future pandemic responses. Overall, this research supports a nuanced view which emphasizes that the details of how and when lockdowns were implemented, as well as the availability of other non-pharmaceutical interventions at the time, played important roles in determining the extent to which lockdowns were or were not effective.

Research suggests that the adoption of lockdowns in the initial COVID surge helped contain transmission and deaths, albeit at high economic and social costs.

The Facts:

• COVID lockdowns began in China in January 2020 and then became widespread – but the decisions to impose lockdowns were made by many national and subnational jurisdictions under conditions of extreme uncertainty, without a full understanding of the costs and benefits for different populations nor a clear timeline of how long they would be maintained. The first COVID lockdown was China’s draconian implementation in Wuhan (China) on January 23, 2020. Subsequently, as COVID spread rapidly across borders and COVID mortality surged, lockdowns were adopted in some form in virtually all countries to contain the spread of the virus. The actual virus’ speed and mode of transmission, recovery and mortality rates were unknown. Additionally, it was unclear whether natural immunity for those who recovered from an infection would be permanent or how the pandemic would be transmitted in different climates and geographical communities, complicating efforts to model its spread and trajectory. Prospects for quickly developing effective vaccines and treatments seemed dim, based on experience with previous viruses and vaccine technologies, raising difficult questions about the duration and impact of the pandemic on population health. There was only limited evidence available on the effectiveness of lockdowns from the deadly 1918 Spanish flu, while the 1997 Avian flu and the 2009 Swine flu epidemics had been more localized and had been combated with strict but targeted lockdowns.
• The double layers of uncertainty about the pandemic and the lockdowns made it difficult to assess the tradeoff between flattening the pandemic’s transmission and mortality curves and the economic and social damage of lockdowns. Lockdowns directly impeded businesses and workers and the functioning of essential services like schools, retirement homes, prisons, and hospitals. Distributional effects added a layer of complexity. It became clear that lockdowns hit certain workers, sectors, and countries much harder than others. Finally, not only did lockdowns raise serious concerns about interference with individual freedom from the onset of the pandemic, but they subsequently turned out to have widespread negative impacts on mental health and on educational achievement. 
• On balance, a careful weighing of the evidence suggests that lockdowns were effective in helping to limit the spread of disease in the early stages of COVID. Several early studies on the health impacts of lockdowns on cases, hospitalization and deaths suggested that they were effective, at least in part (see this survey of studies). For example, one 2020 study found that if Wuhan had not locked down, COVID-19 cases would have been more than 100% higher in the 347 Chinese cities outside Hubei province. However, other studies found that lockdowns were either ineffective in addressing their main health policy goal of reducing cases and deaths or were not the main driver of the epidemic containment. For example, some studies report findings that underline the importance of countries’ pre-conditions (including climate and geography, preparedness, economic support, and obesity, median age, income levels and income dispersions) rather than the lockdown policies, to explain patterns of transmission and mortality. One study found that shelter-in-place requirements in the United States had no significant causal impact on social distancing behavior or the economy because people had already changed their behavior to stay at home as much as possible before the introduction of shelter-in-place orders. However, in a separate study my co-authors and I find evidence that stay-home orders do affect behavior through information transmission and sharing, which amplified voluntary social distancing, at least in the few US counties in which the analysis was conducted.  
• Views on how lockdowns affected economic activity have evolved towards downplaying their impact. Lockdowns were initially associated with sharp declines in activity, suggesting a steep tradeoff between containing the epidemic or facing a deep recession — lives vs. livelihoods (see here and here). But more recent research suggests that the tradeoff with economic activity was less steep since if lockdowns succeed in controlling the epidemic, they can be followed by a rebound in economic activity after a few months that more than offsets the initial economic loss. Other studies also downplay the impact of lockdowns on economic activity. 
• The effectiveness of lockdowns also depended on the details of their implementation. Measures and policies undertaken to limit the spread of COVID in one location could have an impact on more distant locations. One study that looked at actions at the state and county levels in implementing lockdowns in the United States suggested that lockdowns could have been more effective in reducing mobility and contacts if they had been more coordinated across local jurisdictions. But other research in the US context suggests that coordination may be less important than the timing of lockdown adoption (see here and here). This suggests that faster adoption of the lockdowns could have delivered greater reductions in mobility and spread. Research for China, based on network modeling of the pandemic, argues that strict lockdowns can always be substituted by other non-pharmaceutical interventions like mask mandates and voluntary social distancing, except at the very beginning of the pandemic. 
• Eventually, effective vaccines eliminated the need for lockdowns and contained the pandemic. The pandemic lasted much longer than initially anticipated, as virus mutations drove successive waves of infection. However, effective vaccines based on new mRNA technologies were developed much faster than initially anticipated, becoming available just over a year after the initial outbreak, although rolling out quite slowly internationally. Evidence from Europe, from the onset of the pandemic until the end of 2021, shows that many factors — including lockdowns, voluntary social distancing, and government economic support for social distancing, as well as virus mutations — contributed to containing the transmissibility of the virus in 2020. The arrival of the vaccine was critical for the evolution of the epidemic in 2021. Research finds large direct effects of vaccine uptake on individual COVID incidence, equivalent to an 80 percent effectiveness, with indirect effects at the household level about half as large. Variations in vaccine use then contributed to the wide range of experiences across countries and jurisdictions (see here). By early 2022, only China maintained strict lockdowns before suddenly opening up in the fall of 2022. The opening was followed by a major spike in cases but without the catastrophic impact on deaths and hospitalizations that it had feared earlier in the epidemic.